New features
- Added the [`aioduplex()`](https://kchmck.github.io/aiopipe/aiopipe/aiopipe.aioduplex)
function for creating async duplex pipes
Breaking changes
- `send()` method for inheriting pipe renamed to `detach()`
- `open()` now returns a context -- `close()` method removed
- Python 3.7+ is now required for the `get_running_loop()` and `asynccontextmanager()`
functions